Method and device for forming a fluoride or oxyfluoride layer for an optical element for the VUV wavelength range, and optical element including the fluoride or oxyfluoride layer.

Abstract

A method and device for forming a fluoride or oxyfluoride layer for an optical element for the VUV wavelength range, and an optical element including the fluoride or oxyfluoride layer, are provided. The present invention relates to a method for forming a fluoride or oxyfluoride layer (1) for an optical element (2) for use in the VUV wavelength range, comprising depositing an oxide layer (4) and converting the oxide layer (4) into a fluoride or oxyfluoride layer (1) by irradiating said oxide layer (4) with UV / VUV radiation (6) in the presence of an active fluorinating agent (FW). The present invention also relates to an optical setup having at least one such optical element (2) and an associated device for forming a fluoride or oxyfluoride layer (1) for an optical element (2) designed for use in the VUV wavelength range.

Description

[Technical Field]

[0001] Reference to related applications This application claims priority to German Patent Application Publication No. 102022210513.3, filed on 5 October 2022, the entire disclosure thereof is incorporated herein by reference.

[0002] The present invention relates to a method for forming fluorides or oxyfluorides for optical elements for use in the VUV wavelength range. The present invention also relates to optical elements for use in the VUV wavelength range, comprising (at least) one fluoride layer or oxyfluoride layer formed by the method, and to optical mechanisms for the VUV wavelength range having at least one such optical element. The present invention also relates to a device for forming a fluoride layer or oxyfluoride layer for optical elements designed for use in the VUV wavelength range. [Background technology]

[0003] In this application, the VUV wavelength range is interpreted to mean the wavelength range of electromagnetic radiation from 115 nm to 190 nm. The VUV wavelength range is particularly important for microlithography. For example, the VUV wavelength range is used in projection exposure apparatus and wafer or mask inspection apparatus. Optical elements having at least one fluoride layer are often used in such apparatus. Highly reflective optical elements for the VUV wavelength range typically have a fluoride layer, for example, to protect the underlying metal reflective layer from oxidation, to which the radiation is reflected.

[0004] For example, German Patent Application Publication No. 102018211499 also discloses a reflective optical element having a substrate, a metal layer, a metal fluoride layer attached to the metal layer, and an oxide layer attached to the metal fluoride layer, as well as a method for manufacturing the same. In this case, the oxide layer reduces degradation at high radiance levels used in lithography and thus extends the service life of the optical element. Layer stacks consisting of different fluorides or fluorides and oxides may also be used for reflective or anti-reflective coatings of the optical element.

[0005] However, the narrow band gap of most oxides results in high absorptivity in the VUV wavelength range. For this reason, fluorides are often used as layering materials.

[0006] However, the high radiant intensity required in optical mechanisms in the form of wafer or mask inspection equipment and projection exposure equipment leads to degradation of the fluoride and the optical elements as a whole, thereby shortening the service life of the optical elements. This degradation can be suppressed by depositing a high-density fluoride layer.

[0007] In general, high-density solids, especially high-density fluoride layers, can be fabricated using plasma-assisted deposition methods, such as sputtering, ion beam sputtering (IBS), or plasma ion-assisted deposition (PIAD). To compensate for selective sputtering of lighter elements (in this case, O and F), and therefore to maintain the stoichiometry of the deposited layer, a reactive gas is generally supplied during such deposition processes. In the context of oxide layer deposition, such a reactive gas can be, for example, O2. In the case of fluoride deposition, for example, metal fluoride layers are deposited using plasma-assisted electron beam deposition, and F2 is supplied as appropriate, as described in the paper "Plasma-assisted deposition of metal fluoride coatings and modeling the extinction coefficient of as-deposited single layers", M. Bischoff et al., Appl. Opt. 50, 232-238 (2010).

[0008] While F2 is an attractive active fluorinating agent from a scientific standpoint, gaseous fluorine comes with significant challenges in practical use, making it more difficult to use as a process gas. For example, unlike O2, F2 requires a comprehensive safety infrastructure due to its corrosive and toxic properties.

[0009] Other gaseous activated fluorinating agents, such as SF6, CF4, or NF3, are potentially disadvantageous in that momentum transport in plasma-assisted and / or ion-assisted processes incorporates sulfur, carbon, or nitrogen into the deposited layer. Optical performance suffers from this incorporation of these foreign atoms into the deposited layer, particularly in the VUV wavelength range. Specifically, this leads to increased absorption or quenching of the layer.

[0010] Conventional technologies propose post-treatment of fluoride layers to reduce absorption and degradation. Post-treatment means that treatment is carried out after the deposition of the fluoride layer is complete. However, many known post-treatment methods are disadvantageous in that they are carried out at high temperatures, or effective post-treatment requires high temperatures.

[0011] For example, U.S. Patent Application Publication No. 2004 / 0006249 describes a method for post-treatment of a fluoride layer. Preferably, the post-treatment is carried out at a temperature in the range of 10°C to 150°C and a fluorine concentration of 1000 ppm to 100%.

[0012] Furthermore, the literature states that post-treatment using UV light can improve the optical performance of plasma (ion)-assisted deposited fluorides deposited in the DUV wavelength range. For example, the paper by M. Bischoff et al. cited above also describes post-treatment of metal fluoride layers with UV radiation. This paper shows that the initially poor transmittance of LaF3, MgF2, and AlF3 layers in the DUV wavelength range was improved by this post-treatment. During this post-irradiation, the color centers are bleached, and the presumed unsaturated bonds are (superficially) post-oxidized.

[0013] This procedure is feasible for oxides in general and fluorides used in the DUV wavelength range (i.e., wavelengths above 190 nm), but is generally excluded for fluorides in the VUV wavelength range. In the latter case, oxidation causes a loss of optical performance.

[0014] German Patent Application Publication No. 102021200490 also describes a post-treatment of a metal fluoride layer by irradiation, using electromagnetic radiation having at least one wavelength less than 300 nm. The metal fluoride layer is added on a metal layer of a reflective optical element for use in the UV wavelength range. Irradiation results in passivation of the metal fluoride layer, which suppresses degradation of the metal layer. However, this passivation protective layer is typically an oxide layer, which leads to the aforementioned drawbacks.

[0015] UV light irradiation can also be used as an aid in layer deposition during nanostructuring or in the operation of microlithography equipment.

[0016] German Patent Application Publication No. 102018221190 discloses the nanostructuring of a substrate for transmission of radiation in the FUV / VUV wavelength range by introducing an energy input, for example, by irradiation with UV / VUV radiation. In this case, the substrate is crystalline, for example, the substrate is a MgF2 single crystal. This irradiation allows the surface of the MgF2 single crystal to be reorganized to produce an anti-reflective effect.

[0017] German Patent Application Publication No. 102021201477 also discloses a method for operating a microlithographic optical mechanism having an optical element having a fluoride coating or made of a fluoride substrate. In this case, in order to anneal defects in the fluoride, the optical element is irradiated with UV light having a wavelength longer than the wavelength of the operating light of the optical mechanism, which is 300 nm or less, during operation.

[0018] Finally, further methods are known for fabricating fluoride layers or optical elements having fluoride layers, in which other measures are used to reduce absorption and / or degradation.

[0019] For example, German Patent Application Publication No. 102005017742 discloses a method for coating a substrate by plasma-assisted deposition of a coating material, such as a fluoride material. The plasma contains ions with relatively low effective energy, while having a relatively high effective energy per molecule, which is intended to produce a high packing density while simultaneously producing low absorption and contamination of the deposited layer.

[0020] German Patent Application Publication No. 102020208044 discloses a method for fabricating optical elements for the VUV wavelength range, such as mirrors, windows, or beam splitters, having a coating of a fluorine scavenger layer that can be added to a fluoride layer. The purpose of the fluorine scavenger layer is to prevent degradation of the fluoride layer, resulting in a longer lifespan for the optical element. The underlying mechanism is a significant reduction in the mobility of interstitial fluorine atoms by so-called fluorine scavengers within the fluorine scavenger layer.

[0021] Further deformations of the physical gas phase deposition of fluoride layers are also described in U.S. Patent Application Publication No. 2013 / 0122252, Japanese Patent Publication No. 11172421, and Japanese Patent Publication No. 2003193231. [Overview of the project] [Problems that the invention aims to solve]

[0022] In contrast, the object of the present invention is to provide a method and device for forming a fluoride layer or oxyfluoride layer that enables or has high optical performance, as well as an optical element and an optical mechanism having such an optical element. [Means for solving the problem]

[0023] According to the first aspect, this problem is solved by a method of the type described at the beginning, which includes depositing an oxide layer and converting the oxide layer into a fluoride layer or oxyfluoride layer by irradiating the oxide layer with UV / VUV radiation in the presence of an active fluorinating agent. The oxide layer may be deposited directly onto the substrate. However, the oxide layer can also be deposited on a further layer that has been previously added to the substrate (see below).

[0024] In the context of this application, UV / VUV radiation refers to electromagnetic radiation in the wavelength range of 115 nm to 350 nm. Preferably, the fluoride layer is irradiated with VUV radiation in the wavelength range of 115 nm to 190 nm in the presence of an active fluorinating agent (see above).

[0025] In the method according to the present invention, an oxide layer (typically high density) is first deposited in a coating process. Subsequently, the oxide layer is converted to a fluoride layer or an oxyfluoride layer using UV / VUV radiation by supplying a suitable active fluorinating agent. The active fluorinating agent is preferably a gaseous substance that photodissociates as a result of irradiation with UV / VUV radiation, in which case molecules and / or atoms, in particular ionized and / or excited fluorides (hereinafter collectively referred to as fluorine species). The reactive fluorine species cause the chemical conversion of the oxide to fluoride, at least in the surface region of the oxide layer. The entire oxide layer may be converted to a fluoride layer, or it may be converted to a fluoride layer only near the surface, with an oxyfluoride layer formed in the remaining volume. In the latter case, this layer is referred to as the oxyfluoride layer in this application. Complete conversion of the oxide layer to a fluoride layer can be experimentally demonstrated for oxide layer thicknesses of less than about 10 nm. However, as the irradiation duration increases, the (stoichiometric) fluorinated tip can penetrate deeper, so complete conversion can occur even with thicker layers.

[0026] Since the conversion of oxides to fluorides is chemically driven, it is generally possible to use less critical active fluorinating agents, such as NF3, during post-treatment or conversion processes compared to coating processes. Furthermore, the amount of active fluorinating agent required can be reduced compared to coating processes. This reduction in the amount of active fluorinating agent can be compensated for by increasing the duration of the fluorination process. Both of these measures (using less critical active fluorinating agents and reducing the amount of active fluorinating agent) ensure that safety infrastructure requirements can be relaxed compared to fluorine-assisted coating processes using F2.

[0027] In one variation, the oxide layer is preferably deposited using a PVD ("Physical Vapor Deposition") deposition process selected from the group including sputter deposition, particularly magnetron sputtering, ion beam sputtering (IBS), ion beam-assisted sputtering (IBAS), and plasma-ion-assisted deposition (PIAD). The oxide layer is typically deposited using a coating method that allows for the deposition of a high-density layer, and for this purpose, plasma-assisted or ion-assisted processes are advantageous. As detailed above, in order to maintain the stoichiometry of the deposited oxide layer, the oxide layer can be deposited in the presence of a gaseous oxidizing material. For example, reactive gases in the form of O2, H2O, H2O2, ... can be used as the oxidizing material.

[0028] Further modifications involve depositing oxide layers using CVD ("chemical vapor deposition"), specifically including atomic layer deposition (ALD) or plasma-enhanced atomic layer deposition (PEALD). Atomic layer deposition allows for the deposition of extremely thin layers, down to a single atomic layer.

[0029] In a further variation, the oxide layer is deposited in a coating chamber, and the oxide layer is converted into a fluoride or oxyfluoride layer in a fluorination chamber spatially separated from the coating chamber. For the fluorination or conversion of the oxide layer, the substrate on which the oxide layer is deposited is transferred from the coating chamber to the fluorination chamber. The transfer may be carried out manually or automatically.

[0030] Assistive deposition of a fluoride layer in a coating chamber in which an active fluorinating agent is supplied within that range has the problem that the fluorine gas of the active fluorinating agent reacts strongly with high-temperature components in the coating chamber (for example, electrodes of a plasma source or vapor deposition boats used during vapor deposition), resulting in generally significant contamination in the deposited layer. This problem is avoided by the fluorination process described herein, which is performed after coating and generally without using high temperatures. This variant for performing post-treatment or fluorination utilizes a dedicated fluorine-resistant fluorination chamber whose interior has a protective gas atmosphere and is resistant to reactive fluorine species (see below).

[0031] In a further variant, UV / VUV radiation contributes to the photodissociation of the active fluorinating agent, and has a first spectral region whose energy E ph comprises at least one wavelength that is at least equal to the dissociation energy E of the active fluorinating agent diss . In this case, the dissociation energy E diss denotes the energy required to split the chemical bonds of the active fluorinating agent by electromagnetic radiation (light).

[0032] Preferably, the first spectral region predominantly, more preferably exclusively, comprises wavelengths whose energy E ph is at least equal to the dissociation energy E of the active fluorinating agent diss . In this case, the following relationship applies to all photons in the first spectral region. E diss ≦E ph

[0033] It may be further advantageous to limit the first spectral region to the higher-energy side such that the rate of potentially negative and / or competitive effects is suppressed or reduced. Therefore, E UP is preferably selected below a threshold energy above which negative and / or competitive effects are amplified or actually occur in the first place, where E UP is the highest energy of the first spectral region, i.e. E ph ≦EUP The following holds true. Examples of such negative and / or competing effects include light absorption in solids and photodissociation of potential oxidizing species in the gas phase (e.g., O2 and H2O).

[0034] In the advanced form, the highest energy E in the first spectral region UP This is 100% or less, preferably 50% or less, greater than the dissociation energy of the activated fluorinating agent.

[0035] In a further variation of this method, the highest energy in the first spectral region is the band gap energy E of the fluoride or oxyfluoride layer that is formed. G The band gap energy E of the preferably formed fluoride layer or oxyfluoride layer is described below. G This is less than 75%. This reduces light absorption in the fluoride or oxyfluoride layer, and therefore may reduce the formation of point defects (e.g., F centers).

[0036] To reduce the photodissociation of potential oxidizing species in the gas phase (e.g., O2 and H2O), for example, F, F2, F - F * or the effectiveness rate of the formation of potential fluorinated species such as HF r fluorinating However, for example, O, O2, O * , O - , OH * and OH - The efficiency of potential oxidative species such as r oxidizing It will get bigger r fluorinating >r oxidizing Thus, it is even more advantageous to restrict the first spectral region to lower and higher energies.

[0037] In a further variation of this method, the UV / VUV radiation includes a second spectral region for mobilizing atoms on the surface of the oxide layer, at grain boundaries, and / or within the particle volume, the second spectral region being in the energy range of 75% to 100%, preferably 80% to 95%, of the bandgap energy of the fluoride or oxyfluoride layer. Specifically, the energy of the light in the second spectral region must be higher than the binding energy of the corresponding atoms in the solid.

[0038] High-energy electromagnetic radiation near the band edge of the oxide allows surface atoms or atoms to be made mobile without desorption, as described, for example, in German Patent Application Publication No. 102018221190 cited in the abstract. This improved mobility can also contribute to the transport of the surface-supplied active fluorinating agent or fluorine species into the volume of the oxide layer, perhaps mainly through grain boundaries. Thus, this can support deep fluorination, thereby improving optical performance. Furthermore, this improved diffusion can address intrinsic point defects in the particle volume.

[0039] In further modifications, UV / VUV radiation or additional electromagnetic radiation used to irradiate the fluoride or oxyfluoride layer formed during conversion serves to anneal at least one crystal defect in the fluoride or oxyfluoride layer, and includes a spectral region that at least partially overlaps with the absorption region of that at least one crystal defect, preferably including the absorption energy of the crystal defect, and the average energy of this spectral region does not deviate by more than 0.5 eV, more preferably more than 0.25 eV, from the absorption energy of the crystal defect. Irradiation to anneal at least one crystal defect may be performed during or after the conversion of the oxide layer to the fluoride or oxyfluoride layer.

[0040] A potential problem with VUV irradiation is that VUV radiation can introduce crystal defects, particularly F / H center defect pairs, in fluorides or oxyfluorides via single-photon processes. These crystal defects can be annealed using irradiation in a spectral region that at least partially overlaps with the absorption region.

[0041] The absorption energy of a crystal defect is understood to mean the energy or wavelength at which the absorption coefficient of the crystal defect has its maximum value. The absorption region of a crystal defect is interpreted to mean the region where the absorption coefficient is greater than 1 / 100th of the value at the maximum value of the absorption coefficient. The absorption energies of crystal defects in several fluorides related to this application are shown below as examples: MgF2: 260 nm (4.77 eV), AlF3: 190 nm (6.53 eV), 170 nm (7.29 eV), LaF3: 459 nm (2.7 eV), 564 nm (2.2 eV), 729 nm (1.7 eV).

[0042] In a further variation of this method, the oxide layer is irradiated in a protective gas atmosphere. Preferably, the protective gas is permeable to electromagnetic radiation in the UV / VUV wavelength range. It should also be a protective gas that is relatively unreactive to the optically relevant oxides and fluorides. Inert gases in the form of light noble gases (helium, neon, and argon) are particularly suitable as protective gases, with argon being particularly well-suited. Noble gases, especially mixtures of the above noble gases, can also be used as protective gases. As detailed above, the oxide layer is typically irradiated in a fluorination chamber that has its protective gas atmosphere inside.

[0043] In a further variation of this method, the active fluorinating agent comprises at least one substance from the group consisting of F2, HF, XeF2, NF3, CF4, and SF6. As detailed above, an active fluorinating agent with lower criticality than F2, such as NF3, can be selected for conversion or fluorination.

[0044] In a further variation of this method, the partial pressure of the activated fluorinating agent during irradiation of the oxide layer is 0.05-106 The partial pressure is ppmV, preferably 0.075 ppmV to 50 ppmV, more preferably 0.1 ppmV to 10 ppmV. The partial pressure of the active fluorinating agent may be set or specified during irradiation. The partial pressure of the active fluorinating agent can also be controlled to a target value while the oxide layer is being irradiated.

[0045] In further variations, oxide layers are deposited in the form of MgO, Al2O3, La2O3, Gd2O3, CaO, SrO, or BaO layers. The first three oxides specified here and their corresponding fluorides, MgF2, AlF3, and LaF3, are highly relevant to the optics industry. Further specified oxides and their corresponding fluorides, GdF3, CaF2, SrF2, and BaF2, are also used in the optics industry. The chemical drive for the conversion of oxide layers to fluoride or oxyfluoride layers is the corresponding fluoride M X F Y (M = metal, F = fluorine) is an oxide M a O b This works particularly well when the fluoride is more stable. This is especially true for MgO, which has a significant energy driving force for converting the oxide (MgO) to its corresponding fluoride (MgF2). In the case of Al2O3 / AlF3, the formation enthalpies of the oxide and fluoride are almost the same, which is why the conversion works slightly less well than the MgO / MgF2 conversion.

[0046] In further deformation, the oxide layer becomes the MgF2 layer, Mg x O y F z layer, AlF3 layer, Al x O y F z layer, LaF3 layer, La x O y F z layer, GdF3 layer, Gd x O y F z layer, CaF2 layer, Ca x O y F z layer, SrF2 layer, Sr x O y F z Layer, BaF2 layer or Bax O y F z The oxide is converted into a fluoride layer or oxyfluoride layer in the form of a layer. As detailed above, the oxide is typically converted substantially completely to fluoride at or a short distance from the surface of the oxide layer. The oxide layer is typically converted completely to a fluoride layer when the oxide layer is thin, typically on the order of 5 nm to 10 nm. If the oxide layer is thicker, only the volume region of the oxide layer adjacent to the surface of the oxide layer irradiated with VUV radiation may be converted to fluoride, while oxyfluoride is formed at a distance further from the surface. In this case, the conversion results in an oxyfluoride layer M with a fluctuating stoichiometry. x O y F z (M=metal) is generated, meaning that the ratios of x, y, and z vary overall depending on the distance from the surface of the oxyfluoride layer. By increasing the irradiation duration, the (stoichiometric) fluorination tip can penetrate deeper. In this way, even fluoride layers thicker than 10 nm can be formed.

[0047] In a further variation, a metallic reflective layer, specifically an aluminum layer, is deposited on the substrate before the oxide layer is deposited. As mentioned above, the number of materials available for reflecting VUV radiation is limited. Typically, an aluminum layer that can be protected from ambient influences by a high-density layer, such as the one described in German Patent Application Publication No. 102018211499 cited at the beginning, is used as the metallic reflective layer. In the embodiments described herein, a metallic reflective layer, typically in the form of an aluminum layer, is first added to the substrate. Subsequently, the highest possible density oxide layer (e.g., MgO) is deposited on the metallic reflective layer by plasma or ion assistance. The metallic reflective layer and the oxide layer are typically deposited in the same coating chamber. This oxide layer is then converted into a fluoride layer or oxyfluoride layer by the fluorination process described above, for which the coated substrate is typically transferred from the coating chamber to the fluorination chamber. As detailed above, the optical performance of reflective optical elements fabricated using this method is significantly improved for the VUV wavelength range by the conversion of the oxide to an (oxy)fluoride layer.

[0048] In a further development of this modification, an additional fluoride layer is deposited on the substrate before the oxide layer is deposited. In this case, unlike the above, the oxide layer is not deposited directly on the metal reflective layer; instead, a fluoride layer (e.g., MgF2, AlF3, etc.) is deposited first on the metal reflective layer. A thin ion-assisted or plasma-assisted deposited oxide layer is added to this layer stack and converted into a fluoride layer or oxyfluoride layer as detailed above.

[0049] In both of the above cases, this method can be used to realize an optical element in the form of a broadband reflective mirror that is, firstly, well protected from ambient influences, and secondly, has high optical performance.

[0050] Further aspects of the present invention relate to optical elements for use in the VUV wavelength range, comprising a fluoride layer or oxyfluoride layer formed by the method described above. The optical element may be a reflective optical element in the form of a fluoride-protected or passivated metal mirror, for example, as described above. However, the optical element may also be a purely fluoride system without any metal reflective layer, for example, a transmissive optical element with an anti-reflective or highly reflective coating for the VUV wavelength range, or a partially transmissive optical element in the form of a beam splitter, for example. The anti-reflective or highly reflective coating is typically a dielectric multilayer coating comprising one or more fluoride layers.

[0051] Further aspects of the present invention relate to an optical mechanism for the VUV wavelength range, particularly a VUV lithography apparatus or wafer inspection system, comprising at least one optical element as described above. The optical mechanism may be, for example, a (VUV) lithography system, a wafer or mask inspection system, a laser system, and the like.

[0052] Finally, further aspects of the present invention relate to a device for forming a fluoride layer or oxyfluoride layer for an optical element designed for use in the VUV wavelength range by converting an oxide layer to a fluoride layer or oxyfluoride layer, the device comprising: a fluorination chamber; a supply unit for supplying an inert gas and an active fluoride to the fluorination chamber, the inside of which is resistant to the active fluoride and its conversion products; and at least one UV / VUV radiation source for irradiating the oxide layer with UV / VUV radiation in the presence of the active fluoride within the fluorination chamber to convert the oxide layer to a fluoride layer or oxyfluoride layer. The fluorination chamber typically includes a substrate holder used to hold a substrate introduced into the fluorination chamber and on which the oxide layer is added (optionally on a further underlying layer).

[0053] For the advantages obtained by this device, please refer to the above description of the present invention and its modified methods.

[0054] UV / VUV radiation emitted by a UV / VUV radiation source is partially absorbed by an active fluorinating agent. The fluorine species formed as a result of the photodissociation of the active fluorinating agent lead to the conversion of the oxide layer into a fluoride layer or an oxyfluoride layer.

[0055] The UV / VUV radiation source is designed for the photodissociation of active fluorinating agents and typically emits radiation in the wavelength range of preferably 115 nm to 1000 nm, more preferably 120 nm to 170 nm, and particularly 140 nm to 170 nm. For example, the UV / VUV radiation source may be a D2 lamp (deuterium arc lamp), a Xe gas discharge lamp, or a Hg vapor lamp. Alternatively, an F2 excimer laser (with a wavelength of 157 nm) may be used.

[0056] The fluorination chamber can be sealed to an airtight seal. The conversion products of the active fluorinating agent refer to fluorine species and the compounds formed therefrom (e.g., HF). Stability should be interpreted specifically as the formation of a passivation layer on the inside of the fluorination chamber. Specifically, there should be no formation of volatile fluorine compounds that could precipitate on the optical elements processed within the fluorination chamber. The fluorination chamber, particularly its interior, can be at least partially manufactured from a metallic material that, for example, typically does not contain Cr and Ti to prevent corrosion. Specifically, the fluorination chamber may be manufactured from Monel steel.

[0057] Alternatively, the inside of the fluorination chamber may have a fluorine-stabilizing coating to prevent corrosion. Such a coating is preferably added by a galvanic process. Suitable materials are, in particular, Ni, NiP, Pt, or Ru / Rh mixtures.

[0058] The supply unit is preferably designed to introduce an activated fluorinating agent diluted in an inert gas into the fluorination chamber. The supply unit may also include a suitable metering control valve, particularly a mass flow controller, to set the partial pressure of the activated fluorinating agent in the fluorination chamber to a desired value.

[0059] The device preferably further includes a fluorine gas sensor and / or a dedicated sensor for the active fluorinating agent. The device may further include a closed-loop controller for controlling the partial pressure of the active fluorinating agent, which is preferably brought about using measurements from the fluorine gas sensor and / or the dedicated sensor for the active fluorinating agent.

[0060] Therefore, the partial pressure of the activated fluorinating agent may, firstly, be set indirectly by setting the flow rate, or it may be actively controlled using a sensor and a closed-loop controller.

[0061] Preferably, the device may also include one or more additional fluorine-resistant sensors for determining the partial pressure of O2 and / or H2O in the post-processing chamber.

[0062] The device may optionally include a second UV / VUV radiation source that emits UV / VUV radiation in a second spectral region to mobilize atoms on and / or in volume on the surface of the oxide layer and / or the newly formed fluoride or oxyfluoride layer as described above in the context of the above method. In another form thereof, the device may include only one UV / VUV radiation source that emits UV / VUV radiation in the first and second spectral regions.

[0063] To anneal at least one crystal defect in the fluoride layer or oxyfluoride layer, a UV / VUV radiation source and / or a second UV / VUV radiation source may further optionally emit in a spectral region that at least overlaps with the absorption region of the at least one crystal defect. In another embodiment thereof, the device may include one or more further radiation sources that serve to anneal at least one crystal defect in the fluoride layer and further emit electromagnetic radiation in a spectral region that at least partially overlaps with the absorption region of the at least one crystal defect. Therefore, preferably, at least one radiation source is suitable for bleaching crystal defects that occur in the fluoride layer or oxyfluoride layer during conversion. The spectral region can preferably be adapted to the absorption region of the crystal defect or a plurality of absorption regions. Specifically, the further radiation sources or a plurality of further radiation sources may be one or more tunable radiation sources (e.g., based on a broadband primary light source using downstream wavelength selection). In another embodiment thereof, or in addition thereto, a dedicated radiation source for the oxide being converted, or for each of the oxides being converted, may be used.

[0064] Further features and advantages of the present invention will become apparent from reading the following description of exemplary embodiments of the invention with reference to the drawings illustrating details essential to the invention, and from reading the claims. Individual features can be realized individually, alone, or in any desired combination as multiple features in variations of the invention.

[0065] An example embodiment is shown in a schematic diagram and explained below. Further details are as follows. [Brief explanation of the drawing]

[0066] [Figure 1] These schematic diagrams show three snapshots of a method in which a high-density oxide layer is deposited and subsequently converted into a fluoride or oxyfluoride layer by irradiation with VUV radiation in the presence of an active fluorinating agent. [Figure 2] This is a schematic diagram showing the absorption region and spectral region related to the irradiation of the oxide layer. [Figure 3] This is a schematic diagram showing a device for forming a fluoride layer or oxyfluoride layer by converting an oxide layer in the presence of an active fluorinating agent. [Figure 4a-4b] This figure shows the formation enthalpy or the difference in formation enthalpy of three selected oxides and fluorides. [Figure 5a-5b] This figure shows two examples of the procedure for fabricating an optical element for reflecting VUV radiation using the method shown in Figure 1. [Figure 6] This is a schematic diagram showing the optical mechanism for the VUV wavelength range of a VUV lithography apparatus. [Figure 7] This is a schematic diagram showing the optical mechanism for the VUV wavelength range in the form of a wafer inspection system. [Modes for carrying out the invention]

[0067] Figure 1 shows a schematic diagram of the formation of a fluoride layer or oxyfluoride layer 1 of an optical element 2 for use in the VUV wavelength range. Three snapshots M1, M2, and M3 of the substrate 3 of the optical element 2 during the formation of the fluoride layer or oxyfluoride layer 1 are shown.

[0068] The first snapshot M1 shown on the left of Figure 1 shows the substrate 3 after the deposition of a high-density oxide layer 4 made of MgO in the embodiment of the figure. The high-density oxide layer 4 is deposited by known PVD deposition processes, such as sputter deposition, specifically magnetron sputtering, ion beam sputtering (IBS), ion beam-assisted sputtering (IBAS), or plasma ion-assisted deposition (PIAD). Deposition in CVD processes is also possible, which may include atomic layer deposition (ALD) or plasma atomic layer deposition (PEALD), for example.

[0069] The oxide layer 4 is deposited in a coating chamber (not shown in Figure 1). The substrate 3 with the oxide layer 4 deposited is removed from the coating chamber and transferred to a fluorination chamber (also not shown in Figure 1), as indicated by the arrows in Figure 1.

[0070] The second snapshot M2 shown in the center of Figure 1 shows the surface 5 of the oxide layer 4, more precisely the surface 5 of the oxide layer 4 exposed to the ambient environment, during irradiation with UV / VUV radiation 6 in the presence of the active fluorinating agent FW. As a result of the irradiation, the active fluorinating agent FW dissociates, releasing fluorine species F, F2, and F2. * Forms fluorine species F, F2, F * It reacts with the oxide in the oxide layer 4 present on surface 5, converting the oxide into fluoride (in this case, MgF2). For example, the active fluorinating agent FW is NF3, but photodissociates to fluorine species F, F2, F * The supply may be a different substance, specifically at least one substance from the group including F2, HF, XeF2, CF4, and SF6.

[0071] The third snapshot M3, shown on the right of Figure 1, shows the fluoride layer 1 converted from the oxide layer 4 during fluorination. The fluoride layer 1 is (at least nearly) stoichiometric fluoride. The conversion of the high-density oxide layer 4 to the fluoride layer 1 significantly improves the optical performance of the optical element 2. Contrary to what was described above, an oxyfluoride layer may be formed instead of the fluoride layer 1 during the conversion. This occurs when not all oxides in the oxide layer are converted to fluoride. The degree of conversion of oxides in the oxide layer 4 to fluoride depends on various influencing factors, particularly the thickness of the oxide layer 4 and the duration of irradiation.

[0072] In addition, the fluoride layer 1 is irradiated with further electromagnetic radiation 7 during post-treatment in the exemplary embodiment, although this is not essential. This serves the purpose of annealing crystal defects 8 in the fluoride layer 1. In another embodiment, or in addition to this, the further irradiation with electromagnetic radiation 7 may be performed during the irradiation of the oxide layer 4 for the purpose of annealing crystal defects 8 in the already converted portion of the fluoride layer 1.

[0073] Although not shown in Figure 1, the oxide layer 4 may also be heated during irradiation. However, heating is not an essential component of this method.

[0074] Figure 2 shows the absorption and spectral regions related to the irradiation of the oxide layer 4. Energy is plotted on the horizontal axis, and the absorption cross-section is plotted on the vertical axis. Dissociation energy E of the active fluorinating agent FW. diss The absorption cross-sectional area 12 of the newly formed fluoride layer or oxyfluoride layer 1 including the arback tail 12' and the absorption cross-sectional area 13 of the crystal defects 10 within the fluoride layer or oxyfluoride layer 1 are schematically shown.

[0075] The UV / VUV radiation 6 used to irradiate the oxide layer 4 has a first spectral region 14 for the photodissociation of the active fluorinating agent FW. For example, the first spectral region 14 has an energy of E ph The dissociation energy E of the activated fluorinating agent FW diss It includes at least one wavelength that is at least equal to it.

[0076] Furthermore, the highest energy E in the first spectral region 14 UP Here, the dissociation energy E of the activated fluorinating agent FW is diss It is only less than 50% greater (i.e., 1.5 × E) diss (See Figure 2). This is just an example and not mandatory. This suppresses potentially negative and / or competitive effects. The highest energy E in the first spectral region 14. UP The band gap energy E of the oxide layer 4 is GThe following is also possible, preferably the band gap energy E of the oxide layer 4. G It is less than 75% of that.

[0077] Furthermore, the fluoride layer or oxyfluoride layer 1 is further irradiated with, for example, electromagnetic radiation 7, which serves the purpose of annealing at least one crystal defect 10 within the fluoride layer or oxyfluoride layer 1. For this purpose, the further electromagnetic radiation 7 has a spectral region 16 that overlaps with the absorption region 17 of at least one crystal defect 10. In this exemplary embodiment, the spectral region 16 of the further electromagnetic radiation 9 is within the absorption region 17 of the crystal defect 8 which is the F center, but this is not necessarily required. In another form thereof, UV / VUV radiation 6 may include the corresponding spectral region.

[0078] In the embodiment shown in the figure, the spectral region 16 of the further electromagnetic radiation 9 is the absorption energy E of the crystal defect 10 where the absorption cross-section is largest. A This includes, however, it is not necessarily limited to, the absorption region 17 of the crystal defect 10, and the absorption energy E of the crystal defect 10. A It is defined by the decrease (FWHM) of the maximum absorption cross-section in the region to 1 / 100th of its maximum value. Also, the average energy E of the spectral region 16. m The (arithmetic mean) is the absorption energy E of crystal defect 10. A It is advantageous if the deviation does not exceed 0.5 eV, and especially if it does not exceed 0.25 eV.

[0079] Furthermore, the UV / VUV radiation 8 includes a second spectral region 18 for mobilizing atoms on the surface 5, grain boundaries 5' and / or particle volume 5'' of the newly formed fluoride or oxyfluoride layer 1, corresponding to the grain boundaries 5' and particle volume 5'' of the oxide layer 4. In the embodiment shown in the figure, this second spectral region 18 is in the energy range of 75% to 100% of the band gap energy EG of the fluoride or oxyfluoride layer 1. Preferably, the second spectral region 18 is in the band gap energy E of the fluoride or oxyfluoride layer 1. G It is acceptable for it to be in the 80% to 95% range.

[0080] Figure 3 shows a device 60 for forming the fluoride layer or oxyfluoride layer 1 of the optical element 2 in Figure 1 by converting the oxide layer 4 into a fluoride layer or oxyfluoride layer 1. The device 60 includes a fluorination chamber 61, a supply unit 62, and a UV / VUV radiation source 63.

[0081] In this case, the optical element 2, which includes the oxide layer 4 added to the substrate 3 as illustrated, is mounted on a substrate holder 64 that is rotatable around a rotation axis 65 in the fluorination chamber 61. However, the device 60 does not have to include a rotatable substrate holder 64, deviating from the embodiment shown herein.

[0082] The supply unit 62 serves to supply a protective gas in the form of an inert gas IG and an active fluorinating agent FW to the fluorination chamber 61. The supply unit 62 includes a first valve 66 for the controlled supply of the inert gas IG and a second valve 67 for the controlled supply of the active fluorinating agent FW. The second valve 67 is a controllable metering control valve. Thus, the oxide layer 4 can be irradiated in the protective gas atmosphere within the fluorination chamber 61 in the presence of the active fluorinating agent FW. The device 60 further includes a gas outlet 68 for discharging the inert gas IR and reaction products formed during fluorination. In the embodiment shown in the figure, the inert gas IR is argon, but other inert gas IRs, such as other light noble gases such as helium or neon, can also be used. Noble gases, in particular mixtures of the aforementioned noble gases, can also be used as inert gas IRs.

[0083] The UV / VUV radiation source 63 irradiates the oxide layer 4 with UV / VUV radiation 6 in the presence of the active fluorinating agent FW within the fluorination chamber 61. For example, in the embodiment shown in the figure, the UV / VUV radiation 6 enters the fluorination chamber 61 through the MgF2 window 69. The VUV radiation source 63 generates the UV / VUV radiation 6 in the first spectral region 14 described above.

[0084] Furthermore, for example, device 60 includes a second UV / VUV radiation source 70 for irradiating the oxide layer 4 with UV / VUV radiation 7 in the second spectral region 18 described above to mobilize atoms at the surface 5, grain boundaries 5' and / or particle volume 5'' of the oxide layer 4, although this is not required in this case. In the embodiment shown in the figure, the UV / VUV radiation 7 from the second UV / VUV radiation source 70 enters the fluorination chamber 61 through the MgF2 window 69''. Device 60 also includes a further radiation source 71 for irradiating the fluoride layer or oxyfluoride layer 1 formed during conversion with further electromagnetic radiation 7 in the spectral region 17 described above in the context of Figure 2, in order to anneal at least one crystal defect 10 within the fluoride layer or oxyfluoride layer 1. The further electromagnetic radiation 7 from the further radiation source 71 enters the fluorination chamber 61 through a further MgF2 window 69''.

[0085] In principle, instead of at least one of the MgF2 windows 69, 69', and 69”, it is also possible to use windows made of other materials, such as CaF2, SrF2, and / or BaF2, in which case it is critically important that they have sufficient transparency at the wavelengths used.

[0086] The fluorination chamber 61 can be sealed airtight. Furthermore, the interior 72 of the fluorination chamber 61 is resistant to the active fluorinating agent FW and its conversion products. For this purpose, in the illustrated embodiment, to prevent corrosion, the fluorination chamber 61, or at least its interior 72, is formed of a metal in the form of Monel steel, which forms a passivation layer. In principle, the fluorination chamber 61 can also be formed from other corrosion-resistant materials, provided that they do not contain Cr and Ti.

[0087] Alternatively, a corrosion-resistant coating, for example, consisting of NiP, Pt, or a Ru / Rh mixture, can be applied to the inside 72 of the fluorination chamber 61. The corrosion-resistant coating can be applied to the inside 72 of the fluorination chamber 61 by, for example, a galvanic process. Components placed inside the fluorination chamber 61 and in contact with the active fluorinating agent FW are also resistant to the active fluorinating agent FW and its conversion products.

[0088] Furthermore, the device 60 shown here may, for example, not necessarily, be a sensor 73 for measuring the oxygen concentration CO2 in the fluorination chamber 61 and the H2O concentration C in the fluorination chamber 61. H2O Includes a further sensor 74 for measuring.

[0089] For example, the oxygen concentration c in the fluorination chamber 61 during irradiation or conversion of the oxide layer 4. O2 The oxygen concentration is less than 50 ppbV. O2 It should be as low as possible, but may be higher than 50 ppbV. However, oxygen concentration c O2 It is advantageous if the voltage is less than 10 ppmV, preferably less than 1 ppmV, and more preferably less than 100 ppbV.

[0090] Furthermore, in the embodiment shown in the figure, the H2O concentration c in the fluorination chamber 61 when the oxide layer 4 is irradiated. H2O The voltage is less than 100 ppbV. In principle, the H2O concentration c in the fluorination chamber 61 during irradiation of the oxide layer 4. H2O The H2O concentration c should be as low as possible. H2O It may be greater than 100 ppbV. However, the H2O concentration c H2O It is advantageous if the voltage is less than 10 ppmV, preferably less than 1 ppmV, and more preferably less than 500 ppbV.

[0091] Although not essential, the device 60 in the illustrated embodiment controls the partial pressure c of the active fluorinating agent FW in the fluorination chamber 61. FWa sensor 75 for measuring, and the partial pressure c of the active fluorinating agent FW in the fluorination chamber 61 FW further comprising a closed-loop controller 76 for adjusting to a target value, wherein the control is performed using the actual measured value M from the sensor 75 for measuring the partial pressure c of the active fluorinating agent FW in the fluorination chamber 61, and the control of the second valve 67. The sensor 75 may be designed to measure only the partial pressure c of the active fluorinating agent FW FW , but may also be a residual gas analyzer capable of determining the partial pressures of other gases contained in the fluorination chamber 21. Such a residual gas analyzer is capable of fulfilling the functions of the three sensors 73, 74, 75 illustrated in Figure 3. When the second valve 67 is a metering control valve, for example a mass flow control valve, the use of the sensor 75 for measuring the partial pressure c of the active fluorinating agent FW in the fluorination chamber 61 FW can be omitted. FW

[0092] The active fluorinating agent FW is added to the inert gas IR in the supply unit 62. The partial pressure c of the active fluorinating agent FW in the post-treatment chamber 61 during the irradiation of the oxide layer 4 FW is typically 0.05 to 10 6 ppmV, preferably 0.075 ppmV to 50 ppmV, more preferably 0.1 ppmV to 10 ppmV.

[0093] In principle, the chemically and energetically driven conversion of oxides to fluorides always proceeds particularly well when the fluoride M x F y (M = metal, F = fluorine) is more stable than the oxide M a O b . As an example, Figure 4a shows the enthalpies of formation (unit: kJ / mol) of three substance pairs, MgO / MgF₂, Al₂O₃ / AlF₃ and La₂O₃ / LaF₃. Figure 4b shows the enthalpy of formation Δ of oxides for the three chemical elements Mg, Al and La f H 0 ox and the corresponding enthalpy of formation Δ of fluorides f H 0 ​fl shows the difference from. Difference Δ f H 0 ox -Δ f H 0 fl is a positive value, the fluoride of each respective substance pair is more stable than the oxide. As is evident from Figure 6b, this applies only to Mg among the three elements shown, that is, in the case of Mg, there is a significant driving force to convert the oxide to the corresponding fluoride. Experiments have demonstrated a significant reduction in the quenching of Al2O3 by the aforementioned fluorination step. Evaluation of the experiments suggests that the conversion of Al2O3 to AlF3 is slightly less successful than the conversion of MgO to MgF2, consistent with predictions from the enthalpy of formation. Conversion of other oxides to fluorides or oxyfluorides, for example, conversion of Gd2O3 to GdF3, conversion of CaO to CaF2, conversion of SrO to SrF2, or conversion of BaO to BaF2, is also possible.

[0094] The method described above in the context of Figure 1 may be used for the fabrication of different optical elements. In the following, two examples of the fabrication of the optical element 2 in the form of a mirror that reflects radiation in the VUV wavelength range over a broadband are described with reference to Figures 5a and 5b.

[0095] In the embodiment shown in Figure 5a, a substrate 3 is introduced into a coating chamber 59 for a coating process. In the coating process, in the first step, a metallic reflective layer in the form of an aluminum layer 10 is deposited on the substrate 3 using a conventional deposition method. In a subsequent step on the aluminum layer 10, a high-density oxide layer 4, as described in the context of Figure 1, is deposited on the aluminum layer 10 using a plasma-assisted coating method (see above). Since the aluminum layer 10 is protected from environmental influences by the oxide layer 4, the substrate 3 with the aluminum layer 10 and oxide layer 4 deposited can be removed from the coating chamber 59 and introduced into a fluorination chamber 61, which is part of the device 60 shown in Figure 3. Following the coating process, a fluorination process, as described in the context of Figure 3, takes place in the fluorination chamber 61, in which the oxide layer 4, for example in the form of an MgO layer, is converted into a fluoride layer or oxyfluoride layer 1.

[0096] In the embodiment shown in Figure 5b, a (further) fluoride layer 11, possibly made of MgF2, is deposited on the aluminum layer 10 before the deposition of the high-density oxide layer 4. A relatively thin high-density oxide layer 4 is deposited on the fluoride layer 11, as described in the context of Figure 1. In a manner similar to the embodiment described in Figure 5a, the substrate 3 is removed from the coating chamber 59 and transferred to the fluorination chamber 61, where a fluorination process takes place to convert the oxide layer 4 into a fluoride layer 1. In the embodiment shown in Figure 5b, the oxide layer 4 deposited on the further fluoride layer 11 is relatively thin, typically 5-10 nm, and therefore, unlike the embodiment described in Figure 5a, it is converted into a fluoride layer 1 rather than an oxyfluoride layer. However, thicker embodiments of the oxide layer 4 are also possible.

[0097] The optical element 2 described above, which includes a fluoride layer or an oxyfluoride layer 1, may be used in different optical mechanisms for the VUV wavelength range.

[0098] Figure 6 shows the optical mechanism for the VUV wavelength range of a VUV lithography apparatus 21. The VUV lithography apparatus 21 includes two optical systems, namely an illumination system 22 and a projection system 23. The VUV lithography apparatus 21 further includes a radiation source 24, which may be, for example, an excimer laser.

[0099] The radiation 25 emitted by the radiation source 24 is directed using an illumination system 22 so that a mask 26, also called a reticle, is illuminated by the radiation 25. In the embodiment shown in the figure, the illumination system 22 includes a housing 32 in which both a transmitted optical element and a reflected optical element are housed. The figure typically shows a transmitted optical element 27 that focuses the radiation 25 and a reflected optical element 28 that deflects the radiation.

[0100] The mask 26 includes on its surface an optical element 29, such as a structure to be transferred to a wafer, which is exposed using a projection system 23 in order to fabricate a semiconductor component. In the embodiment shown in the figure, the mask 26 is configured as a transmissive optical element. In another embodiment, the mask 26 may be configured as a reflective optical element.

[0101] In the illustrated embodiment, the projection system 22 has at least one transmission optical element. The illustrated embodiment typically shows two transmission optical elements 30, 31, which play a role in reducing the structure on the mask 26 to a size desirable for exposure of the wafer 29.

[0102] In both the illumination system 22 and the projection system 23, various transmissive, reflective, or other optical elements can be combined with each other as required, including in more complex configurations. Optical mechanisms without transmissive optical elements can also be used for VUV lithography.

[0103] Figure 7 shows an optical mechanism for the VUV wavelength range in the form of a wafer inspection system 41, which may also be a mask inspection system. The wafer inspection system 41 has an optical system 42 having a radiation source 54, and radiation 55 from the radiation source 54 is directed onto a wafer 49 using the optical system 42. For this purpose, the radiation 55 is reflected to the wafer 49 from a concave mirror 46. In the case of a mask inspection system, the wafer 49 can be replaced with a mask under inspection. The radiation reflected, deflected and / or refracted by the wafer 49 is directed to a detector 50 for further evaluation via a transmission optical element 47 and a further concave mirror 48 similarly associated with the optical system 42. The wafer inspection system 41 further includes a housing 52 in which two mirrors 46, 48 and a transmission optical element 47 are housed. The radiation source 54 may be, for example, strictly one radiation source or a combination of multiple individual radiation sources to provide a substantially continuous radiation spectrum. In modified embodiments, it is also possible to use one or more narrowband radiation sources 54.

[0104] At least one of the optical elements 27, 28, 30, and 31 of the VUV lithography apparatus 21 shown in Figure 6, and at least one of the optical elements 46, 47, and 48 of the wafer inspection system 41 shown in Figure 7, are designed as described above. Therefore, at least one of the optical elements 27, 28, 30, 31, 46, 47, and 48 includes (at least) one fluoride layer or oxyfluoride layer formed or fabricated using the method described above.

Claims

1. A method for forming a fluoride layer or oxyfluoride layer (1) for an optical element (2) for use in the VUV wavelength range, Depositing an oxide layer (4), By irradiating the oxide layer (4) with UV / VUV radiation (6) in the presence of an activated fluorinating agent (FW), the oxide layer (4) is converted into the fluoride layer or oxyfluoride layer (1), Methods that include...

2. The method according to claim 1, characterized in that the oxide layer (4) is deposited using a PVD deposition process.

3. The method according to claim 2, wherein the oxide layer (4) is deposited using a sputtering deposition process.

4. The method according to claim 3, wherein the sputtering deposition process is selected from the group including magnetron sputtering, ion beam sputtering (IBS), and ion beam assisted sputtering (IBAS).

5. The method according to claim 2, wherein the oxide layer (4) is deposited using plasma ion-assisted deposition (PIAD).

6. The method according to claim 1, characterized in that the oxide layer (4) is deposited using a CVD deposition process.

7. The method according to claim 6, wherein the CVD deposition process includes an atomic layer deposition (ALD) process or a plasma atomic layer deposition (PEALD) process.

8. The method according to any one of claims 1 to 7, characterized in that the oxide layer (4) is deposited in a coating chamber (59), and the oxide layer (4) is converted into the fluoride layer or oxyfluoride layer (1) in a fluorination chamber (61) spatially separated from the coating chamber (59).

9. The UV / VUV radiation (6) contributes to the photodissociation of the activated fluorinating agent (FW), and the energy (E ph ) is at least the dissociation energy (E) of the activated fluorinating agent (FW). diss The method according to claim 1, characterized in that it has a first spectral region (14) that includes at least one wavelength equal to ).

10. The highest energy (E) of the first spectral region (14) UP ) is the dissociation energy (E) of the activated fluorinating agent (FW). diss The method according to claim 9, characterized in that it is greater by 100% or less than ).

11. The highest energy (E) of the first spectral region (14) UP ) is the band gap energy (E) of the fluoride layer or the oxyfluoride layer (1). G The method according to claim 10, characterized in that it is as follows:

12. The UV / VUV radiation (8) includes a second spectral region (18) for mobilizing atoms at the surface (4), grain boundaries (5'), and / or particle volume (5'') of the fluoride layer or the oxyfluoride layer (1), wherein the second spectral region (18) has a band gap energy (E) of the fluoride layer or the oxyfluoride layer (1). G The method according to any one of claims 1 to 7, characterized in that it is in the energy range of 75% to 100% of ).

13. The method according to any one of claims 1 to 7, characterized in that the UV / VUV radiation (8) or further electromagnetic radiation (9) used to irradiate the fluoride layer or oxyfluoride layer (1) formed during the conversion serves to anneal at least one crystal defect (8) of the fluoride layer or oxyfluoride layer (1) and includes a spectral region (16) that at least partially overlaps with the absorption region (17) of the at least one crystal defect (8).

14. The spectral region (16) corresponds to the absorption energy (E) of the crystal defect (8). A The method according to claim 13, including ).

15. the average energy (E of the spectral region (16) m ) does not deviate by more than 0.5 eV from the absorption energy (E of the crystal defect (8) A ), according to the method of claim 14.

16. The method according to any one of claims 1 to 7, characterized in that the oxide layer (4) is irradiated in a protective gas atmosphere.

17. The activated fluorinating agent (FW) is F 2 HF, XeF 2 NF 3 CF 4 SF 6 The method according to any one of claims 1 to 7, characterized by comprising at least one substance selected from the group consisting of the following.

18. During the irradiation of the oxide layer (4), the partial pressure (c) of the activated fluorinating agent (FW) FW ) is 0.05 to 10 6 The method according to any one of claims 1 to 7, characterized in that it is ppmV.

19. The oxide layer (4) consists of an MgO layer and an Al layer. 2 O 3 Layer, La 2 O 3 layer, Gd 2 O 3 The method according to any one of claims 1 to 7, characterized in that the layers are deposited in the form of a CaO layer, a SrO layer, or a BaO layer.

20. The oxide layer (4) is MgF 2 layer, Mg x O y F z layer, AlF 3 Layer, Al x O y F z layer, LaF 3 Layer, La x O y F z layer, GdF 3 layer, Gd x O y F z layer, CaF 2 layer, Ca x O y F z layer, SrF 2 Layer, Sr x O y F z Layer, BaF 2 Layer or Ba x O y F z The method according to any one of claims 1 to 7, characterized in that it is converted into a fluoride layer or oxyfluoride layer (1) in the form of a layer.

21. The method according to any one of claims 1 to 7, characterized in that a metal reflective layer is deposited on the substrate (3) before the oxide layer (4) is deposited.

22. The method according to claim 21, characterized in that a further fluoride layer (11) is deposited on the substrate (3) before the oxide layer (4) is deposited.

23. A method for manufacturing an optical element (2) for use in the VUV wavelength range, A method for manufacturing an optical element (2) for use in the VUV wavelength range, comprising forming a fluoride layer or oxyfluoride layer (1) using the method described in any one of claims 1 to 7, wherein the optical element (2) for use in the VUV wavelength range comprises the fluoride layer or oxyfluoride layer (1).

24. A method for manufacturing an optical mechanism for the VUV wavelength range, A method for manufacturing an optical mechanism, comprising manufacturing at least one optical element (27, 28, 30, 31, 46, 47, 48) using the manufacturing method described in claim 23, wherein the optical mechanism for the VUV wavelength range includes the at least one optical element.

25. A device for forming a fluoride layer or oxyfluoride layer (1) for an optical element (2) designed for use in the VUV wavelength range, by converting an oxide layer (4) to a fluoride layer or oxyfluoride layer (1), - Fluorination chamber (61), - A supply unit (62) for supplying an inert gas (IG) and an active fluorinating agent (FW) to the fluorination chamber (61), wherein the inside (72) of the fluorination chamber (61) is resistant to the active fluorinating agent (FW) and its conversion products, - A device (60) comprising at least one UV / VUV radiation source (63, 70) for irradiating the oxide layer (4) with UV / VUV radiation (8) in the presence of the active fluorinating agent (FW) within the fluorination chamber (61) in order to convert the oxide layer (4) into the fluoride layer or the oxyfluoride layer (1).

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